The invention described in the present application is an improvement over that described in Sanford, U.S. Pat. No. 2,593,701, issued Apr. 22, 1952.
In domestic or institutional shower facilities, textile mills and like industrial installations where supply of constant temperature water is required, it is important that means be present for compensating the flow of hot and cold water for variations in the water supply pressure. The problem occurs most commonly in domestic shower baths where sudden external draw-off of cold water in the system lower the cold water supply pressure to the shower head. This results in hot or even scalding water being discharged from the shower head with resulting hazard, or at least discomfort, to the user.
It is the general purpose of the present invention to provide an improved valve useful in the foregoing and other situations to eliminate temperature variations caused by pressure fluctuations occurring in either the hot or cold water supply lines.
It is a further object of the present invention to provide a pressure compensating valve of the class described in which the parts are sealed against each other in the assembly of the valve without distortion and without requiring that extremely close tolerances be held on the interfitting parts.
Still another object of the present invention is the provision of a valve of the class described which is sealed against internal leakage.
Still a further object of the present invention is the provision of a valve of the class described which in operation is free from problems of water hammer.
Yet another object of the present invention is the provision of a pressure compensating valve of the class described which is characterized by a high degree of sensitivity, simplified construction, and the utilization of a minimum number of easily assembled component parts.
The foregoing and other objects of the invention are achieved by the provision of an automatic pressure compensating valve which, broadly considered, comprises a unitary valve body apertured to provide a central axial cavity open at one end. A sleeve is disposed within the cavity. The valve body has hot and cold water inlet and outlet passages. The sleeve has ports providing fluid communication between the hot water inlet and outlet passages and between the cold water inlet and outlet passages of the body, respectively.
A pressure balancing piston is disposed for movement within the sleeve. It has surfaces acted upon by the fluid pressure in both the hot and cold water inlet passages, and is responsive thereto. Closure means carried by the piston inversely obstructs the sleeve ports between the hot water inlet and outlet passages and the sleeve ports between the cold water inlet and outlet passages in response to a variation in the ratio of fluid pressures in the inlet passages.
O-ring seal means on the closure means prevent leakage of hot or cold water from one side to the other of the piston.
Resilient pads on each end of the piston prevent water hammer during operation of the valve.